1. Field
The present disclosure relates to a color separation element array, an image sensor including the color separation element array, and an image pickup apparatus including the color separation element array, and more particularly, to a color separation element array that may improve a color separation efficiency at an edge portion thereof where light is obliquely incident, and to an image sensor and an image pickup apparatus using the color separation element array.
2. Description of the Related Art
Color display devices or color image sensors display an image of various colors or detect a color of incident light by using a color filter. An RGB color filter method, in which, for example, a green filter is arranged at two pixels of four pixels and a blue filter and a red filter are arranged in the other two pixels, is most widely employed by a currently used color display device or color image sensor. In addition to the RGB color filter method, a CYGM color filter method may be employed in which color filters of cyan, yellow, green, and magenta, which are complementary colors, are respectively arranged at four pixels.
However, a color filter may have a low light use efficiency because the color filter absorbs light of other colors except for filtered light. For example, when an RGB color filter is in use, only ⅓ of the incident light is transmitted and the other portion, that is, ⅔, of the incident light is absorbed. Accordingly, the light use efficiency may be about 33%. Accordingly, for the color display device or a color image sensor, most of a light loss is generated in the color filter.
Recently, to improve the light use efficiency of the color display device or color image sensor, a color separation element is being used instead of the color filter. The color separation element may separate colors of the incident light by using the diffraction or refraction characteristics of a light that varies according to a wavelength of the light. The colors separated by the color separation element may be transferred to pixels corresponding to the transferred colors. Accordingly, use of the color separation element may achieve a higher light use efficiency as compared to a case of using the color filter.